1. Field of the Invention
The present invention relates to an ink container for containing ink to be supplied to an ink jet recording head, ink, and an ink jet recording apparatus using the ink container.
2. Description of the Related Art
The ink container used with an ink jet recording apparatus is required to be capable of properly supplying the amount of the ink corresponding to the amount of the ink ejected from a recording head during the recording operation and to be free of ink leakage through the ejection outlets of the recording head when the recording operation is not executed.
In the case that the ink container is an exchangeable type, it is required that the ink container can be easily mounted or demounted relative to the recording apparatus without ink leakage, and that the ink can be supplied to the recording head with certainty.
A conventional example of an ink container usable with the ink jet recording apparatus is disclosed in Japanese Laid-Open Patent Application No. 87242/1988 (first prior art), in which the ink jet recording cartridge has an ink container containing foamed material and having a plurality of ink ejecting orifices. With the ink container, the ink is contained in the porous material such as foamed polyurethane material, and therefore, it is possible to produce negative pressure by the capillary force in the foamed material and to prevent the ink leakage from the ink container.
Japanese Laid-Open Patent Application No. 522/1990 (second prior art) discloses an ink jet recording cartridge in which a first ink container and a second ink container are connected with a porous material, and a second ink container and an ink jet recording head are connected with a porous material. In this prior art, the porous material is not contained in the ink container, and it is disposed only in the ink passage, by which the use efficiency of the ink is improved. By the provision of the secondary ink containing portion, the ink flowing out of the first ink container due to the air expansion in the first ink container due to the temperature increase (pressure decrease), is stored, by which the vacuum in the recording head during the recording operation is maintained substantially constant.
However, in the first prior art, the foamed material is required to occupy substantially the entire space in the ink container layer, and therefore, the ink capacity is limited, and in addition, the amount of the non-usable remaining ink is relatively large, that is, the use efficiency of the ink is poor. These are the problems therewith. In addition, it is difficult to detect the remaining amount of the ink, and it is difficult to maintain substantially constant vacuum during the ink consumption period. These are additional problems.
In the second prior art, when the recording operation is not carried out, the vacuum producing material is disposed in the ink passage, and therefore, the porous material contains a sufficient amount of the ink, and the production of the negative pressure by the capillary force of the porous material is insufficient, with the result that the ink is leaked through the orifices of the ink jet recording head by small impact or the like. This is a problem. In the case of an exchangeable ink cartridge in which the ink jet recording head is formed integrally with the ink container, and the ink container is mounted on the ink recording head, the second prior art is not usable. This is another problem.
Japanese Laid-Open Patent Applications Nos. 67269/1981 and 98857/1984 disclose an ink container using an ink bladder urged by a spring. This is advantageous in that the internal negative pressure is stably produced at the ink supply portion, using the spring force. However, these system involve problems that a limited configuration of the spring is required to provide a desired internal negative pressure, that the process of fixing the ink container to the bladder is complicated, and therefore, the manufacturing cost is high. In addition, for a thin ink container, the ink retaining ratio is small.
Japanese Laid-Open Patent Application No. 214666/1990 discloses a separated chamber type in which the inside space of the ink container is separated into a plurality of ink chambers, which communicate with each other by a fine hole capable of providing the vacuum pressure. In the separate chamber type, the internal negative pressure at the ink supply portion is produced by the capillary force of the fine opening communicating the ink chambers. In this system, the structure of the ink container is simpler than the spring bladder system, and therefore, it is advantageous from the standpoint of the manufacturing cost and the configuration of the ink container in not limited from the structure. However, the separated chamber type involves the problem that when the ink container position is changed, the fine opening becomes short of ink depending on the remaining amount of the ink with the result of instable internal vacuum pressure even to the extent that the ink is leaked, and therefore, the ink container is imposed by limitation in the handling thereof.
Also, in the technical fields of recording using ink, there is a contact recording technique for use with plotters. In this contact recording technique, the ink supply is typically made to a recording core or wick having ink absorbability and retainability like a felt-tipped pen.
One example of the ink supply form in the above contact recording technique is Japanese Laid-Open Utility Model Application No. 57-16385. This discloses a recording instrument pen relying on the use of a recording core (porous ink absorptive core) for recording in contact with the recording medium.
The invention which this document discloses adopts a constitution comprising a central chamber having a recording core, a first flocculent fiber in contact with the recording core, and a second flocculent fiber having a small amount of ink absorbed in the upper atmosphere communicating port side and being less permeable to the ink than the first flocculent fiber, and a closed type ink storing chamber from which the ink can be supplied via a communicating hole to either side of the central chamber.
With this constitution, air within the closed type ink storing chamber expands due to rises in the ambient temperature, so that the ink within the closed type ink storing chamber flows into the first flocculent fiber. The ink exceeding the acceptable impregnated amount of the first flocculent fiber is impregnated by the second flocculent fiber, thereby preventing the ink from overflowing from the recording core and dripping down.
Also, there is provided a groove of fixed width to cause the expanded air to escape into the atmosphere communicating port when one of two closed type ink storing chambers is only filled with the air. The groove extends from the uppermost end to the lowermost end of a lateral surface different from that of a partition wall between the central chamber and the closed type ink storing chamber, as disclosed above.
However, in the above contact recording instrument pen, no attention is paid to the stable generation of negative pressure serving to prevent ink leakage from the recording unit in the ink jet technique which involves a non-contact recording.
Also, the consumption of the ink from the ink storing chambers on both sides is not necessarily identical, but it is pointed out that the ink of one ink storing chamber may be possibly exhausted ahead. Some attention is paid concerning the ink leakage from the recording core due to environmental changes in this case, but in the ink jet recording field, some problem such as the disruption of ink flow passage, or the penetration of air bubbles into the recording portion may occur.
To solve the above background problems, the present inventors have previously made applications or as the ink vessel suitable for the ink jet print technical field, an ink jet cartridge having both features of the capability of supplying excellently the ink in the amount corresponding to that discharged from the recording head during printing, and the expedience of having no ink leakage from the discharge ports when the printing is not performed (Japanese Laid-Open Patent Application No. 4-198474, Japanese Laid-Open Patent Application No. 4-198681).
Herein, it has been found that the fundamental constitution effective for the ink jet characteristics is one having a first accommodating chamber which is a negative pressure generating member receiving portion having an atmosphere communicating portion for communicating to the atmosphere as well as receiving a negative pressure generating member, and a second accommodating chamber which communicates to the first accommodating chamber but lies in substantially closed state, and which is an ink storing portion for directly storing the ink to be supplied to the first accommodating chamber (hereinafter referred to as a presupposed constitution).
Because this constitution has a tank structure in which the negative pressure can be made substantially constant for most of the term from the initiation of using the head cartridge to the termination thereof, it is possible to provide a replacement-type head cartridge and an ink jet head and a printer which can cope with the high speed recording.
Further, in recent years, the ink jet recording art is not only applied to the printer, but also employed in the communication technical field such as facsimile, the copying machine field usable for the large paper (large size), and in the printing field onto cloth. With this trend, the larger capacity of the ink vessel is desired for the apparatus.